Sanford, NC, USA
N1953H
PIPER PA-32-300
The private pilot was in the traffic pattern at the intended destination airport when the airplane experienced a loss of engine throttle control. Unable to reach the runway, he elected to perform a forced landing in a nearby field. During the landing, the airplane struck a fence post, which resulted in substantial damage to the left wing of the airplane. Postaccident examination revealed that the throttle lever clevis and throttle cable became separated from the throttle arm, which resulted in the engine being unresponsive to throttle input; thus, the pilot could not apply power to the engine from the idle position. No evidence of metal deformation existed on either the throttle lever clevis or on the throttle cable; however, examination of the cotter pin revealed that one prong was separated and unable to be located. Examination of the remaining portion of the cotter pin revealed that it was twice as long as manufacturer-approved guidance required. Examination of the clevis for the propeller cable linkage revealed that the cotter pin prongs exceeded Federal Aviation Administration Advisory Circular 43-13-1B guidance by allowing the prong to exceed the pin diameter and the cotter pin prongs were not seated firmly against the shank. A review of maintenance records did not reveal when the cotter pin was replaced. The hardware was likely installed using the incorrect safetying technique and the improper length of cotter pin. This allowed the prong to become caught and subsequently fracture on nearby hardware, which resulted in the cotter pin becoming unsecured and separating from the linkage pin. Subsequently, the linkage pin detached, which allowed the throttle lever clevis and cable to separate from each other. The last annual inspection occurred 2 weeks and less than 1 flight hour before the accident. It is likely that the mechanic did not detect the incorrect cotter pin and safetying technique due to its location; the location was such that it would have been difficult for the mechanic to see.
HISTORY OF FLIGHT On February 27, 2013, about 1553 eastern standard time, a Piper PA-32-300, N1953H, experienced a loss of engine throttle control during an approach to Raleigh Executive Jetport at Sanford-Lee County Airport (TTA), Sanford, North Carolina. The pilot subsequently performed a forced landing to a nearby field. The private pilot was not injured. The airplane was registered to Rekme Aero LLC and was operated under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed and no flight plan had been filed for the flight that originated from Siler City Municipal Airport (5W8), Siler City, North Carolina, about 1543. According to the pilot, prior to departure the airplane had 84 gallons of fuel on board. The preflight, engine run-up, takeoff, and climb to 3000 feet were accomplished with no abnormalities detected. He entered the traffic pattern for landing at TTA, and reduced the engine power to idle. He noted that neither resistance nor change in engine rpm was detected when he adjusted the throttle lever. He attempted to maintain altitude and perform a shallow left turn in order to attempt another approach. However, as back pressure on the yoke was applied, the stall warning horn activated and he attempted to land in a nearby field. The airplane touched down in a level attitude, became airborne while crossing a gravel road, touched down again, impacted a fence post with the left wing at the wing root, and then came to rest about 200 yards past the fence post. PERSONNELL INFORMATION The pilot, age 44, held a private pilot certificate for airplane single-engine land and a third class medical certificate issued February 14, 2012 with no limitation. The pilot reported 401 total flight hours with 347 total flight hours as pilot in command and 228 total flight hours in the accident airplane make and model. AIRCRAFT INFORMATION The low-wing, six-seat, single-engine airplane was manufactured in 1977 and equipped with a Lycoming IO-540-K1G5, 300-hp engine. According to the pilot, the airplane's most recent annual inspection was completed on February 15, 2013. At the time of the inspection the airplane had accumulated 4,014 total flight hours and the engine had accumulated 3,610 total hours time in service, including 494 hours since overhaul. METEORGOLOGICAL INFORMATION The 1555 recorded weather observation at TTA, included wind from 230 degrees at 8 knots, with variable wind direction recorded between 190 and 270 degrees, 10 miles visibility, broken clouds at 100 feet above ground level (agl) and 4,800 feet agl, temperature 15 degrees C, dew point 4 degrees C; barometric altimeter 29.73 inches of mercury. AIRPORT INFORMATION The airport was a publically owned airport and at the time of the accident did not have an operating control tower. The airport was equipped with one runway designated as runway 3/21, which was 6,500 feet-long and 100 feet-wide WRECKAGE AND IMPACT INFORMATION The airplane came to rest approximately 200 yards from a gravel road. It came to rest upright and on the right main and nose landing gear. The left wing was resting on the ground and exhibited impact damage on the leading edge extending from the fuselage outboard approximately 3 feet. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the throttle cable, which was attached to the fuel servo, would not operate with throttle movement. Due to the damage of the surrounding structure a detailed examination was unable to be conducted. During recovery of the airplane, the pin, washer, and a portion of the cadmium plated cotter pin associated with the throttle lever clevis were located on the floor of the cockpit beneath the throttle quadrant. Photographic examination of the cotter pin revealed that one prong of the cotter pin was unable to be located. The remaining portion of the cotter pin measured approximately ¾ of an inch in length. A photograph of the cotter pin associated with the propeller lever, adjacent to the throttle lever, revealed that the clevis pin remained in place and was secured with a cotter pin; however, the cotter pin exceeded the clevis diameter and the prongs were not seated firmly against the clevis pin. ADDITIONAL INFORMATION FAA Advisory Circular (AC) 43 13-1B AC 43 13-1B "Acceptable Methods, Techniques, and Practices – Aircraft Acceptance and Repair" Chapter 7 "Aircraft Hardware, Control Cables, and Turnbuckles" Section 6 "Pins 7-127 Securing with Cotter Pins" states in part "…the diameter of the cotter pins selected for any application should be the largest size that will fit consistent with the diameter of the cotter pin hold and/or the slots in the nut." That section also contains a note that states in part "In using the method of cotter pin safetying…ensure the prong, bent over the bolt, is seated firmly against the bolt shank, and does not exceed bolt diameter…" That section also includes descriptive drawings of the proper way to secure the cotter pin. Airplane Manufacturer's Guidance According to the airplane manufacturer's parts catalog applicable to this make and model, the approved cotter pin to secure the throttle linkage pin was an AN380-2-1. A review of publically available guidance revealed that an AN380-2-1 cotter pin would have a diameter of 1/16 of an inch and be 3/8 inch long.
The installation of an incorrect length of cotter pin on the throttle linkage clevis pin by maintenance personnel at an undetermined time, which resulted in the pin coming loose and the loss of throttle control.
Source: NTSB Aviation Accident Database
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